Rulebuilder: allow saving incomplete rule when switching to source

I want to start building a rule in rulebuilder and then switch seamlessly to source code for further editing.
Currently, rulebuilder asks if it should save before switching. However, if there is an error or the rule is incomplete, the save fails and the work is lost anyway.

I expect the rulebuilder content to show up in the source editor, even if it is has problems. That's why I am still editing. It's particularly frustrating when you acknowledge the save prompt, just to find that you lost your work regardless.